Likewise, insulation not properly tucked in under the roof and at the top of the wall panels can be exposed to condensation and wind-blown rain, causing underside corrosion of the roof panel.
(picture in origional post),
Installation practices that allow the insulation to become continually wet simply should be avoided. Fiberglass blanket insulation under Galvalume® roofs needs to be installed in such a way that all vapor barrier seams are sealed, and punctures, penetrations or holes in the vapor barrier are repaired. Condensation of water vapor on the underside of the roof, along with saturation of the insulation, can cause inside-out corrosion.
Certain types of field-applied spray-on insulation contain chemical fire retardants that may be corrosive to Galvalume® sheet. Check with insulation manufacturers before using such products.